bal_strategy_history.c

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 *
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/**
 * @file    bal_strategy_history.c
 * @author  foxBMS Team
 * @date    2020-05-29 (date of creation)
 * @updated 2022-10-27 (date of last update)
 * @version v1.4.1
 * @ingroup APPLICATION
 * @prefix  BAL
 *
 * @brief   Driver for the Balancing module
 *
 */
 
/*========== Includes =======================================================*/
#include "bal_strategy_history.h"
 
#include "battery_cell_cfg.h"
 
#include "bms.h"
#include "database.h"
#include "os.h"
#include "state_estimation.h"
 
/*========== Macros and Definitions =========================================*/
 
/*========== Static Constant and Variable Definitions =======================*/
/** local storage of the #DATA_BLOCK_BALANCING_CONTROL_s table */
static DATA_BLOCK_BALANCING_CONTROL_s bal_balancing = {.header.uniqueId = DATA_BLOCK_ID_BALANCING_CONTROL};
/** local storage of the #DATA_BLOCK_CELL_VOLTAGE_s table */
static DATA_BLOCK_CELL_VOLTAGE_s bal_cellVoltage = {.header.uniqueId = DATA_BLOCK_ID_CELL_VOLTAGE};
 
/** contains the state of the contactor state machine */
static BAL_STATE_s bal_state = {
    .timer                  = 0,
    .stateRequest           = BAL_STATE_NO_REQUEST,
    .state                  = BAL_STATEMACH_UNINITIALIZED,
    .substate               = BAL_ENTRY,
    .lastState              = BAL_STATEMACH_UNINITIALIZED,
    .lastSubstate           = 0,
    .triggerEntry           = 0,
    .errorRequestCounter    = 0,
    .initializationFinished = STD_NOT_OK,
    .active                 = false,
    .balancingThreshold     = BAL_DEFAULT_THRESHOLD_mV + BAL_HYSTERESIS_mV,
    .balancingAllowed       = true,
    .balancingGlobalAllowed = false,
};
 
/*========== Extern Constant and Variable Definitions =======================*/
 
/*========== Static Function Prototypes =====================================*/
/** Activates history based balancing */
static void BAL_ActivateBalancing(void);
 
/**
 * @brief   Deactivates history based balancing
 * @details The balancing state of all cells in all strings set to inactivate
 *          (that is 0) and the delta charge is set to 0 As. The balancing
 *          enable bit is deactivate (that is 0).
 */
static void BAL_Deactivate(void);
 
/**
 * @brief   State machine subfunction to check if balancing is allowed
 * @details Checks if balancing is allowed. If it is it transfers in the actual
 *          balancing state.
 */
static void BAL_ProcessStateCheckBalancing(void);
 
/** State machine subfunction to balance the battery cell */
static void BAL_ProcessStateBalancing(void);
 
/** State machine subfunction to check for voltage imbalances */
static bool BAL_CheckImbalances(void);
 
/** State machine subfunction to compute the imbalance of all cells */
static void BAL_ComputeImbalances(void);
 
/*========== Static Function Implementations ================================*/
 
static void BAL_ActivateBalancing(void) {
    float cellBalancingCurrent = 0.0f;
    uint32_t difference        = 0;
 
    DATA_READ_DATA(&bal_balancing, &bal_cellVoltage);
 
    for (uint8_t s = 0u; s < BS_NR_OF_STRINGS; s++) {
        uint16_t nrBalancedCells = 0u;
        for (uint8_t c = 0u; c < BS_NR_OF_CELL_BLOCKS_PER_STRING; c++) {
            if (bal_state.balancingAllowed == false) {
                bal_balancing.balancingState[s][c] = 0;
            } else {
                if (bal_balancing.deltaCharge_mAs[s][c] > 0) {
                    bal_balancing.balancingState[s][c] = 1;
                    nrBalancedCells++;
                    cellBalancingCurrent = ((float)(bal_cellVoltage.cellVoltage_mV[s][c])) /
                                           BS_BALANCING_RESISTANCE_ohm;
                    difference       = (BAL_STATEMACH_BALANCINGTIME_100ms / 10) * (uint32_t)(cellBalancingCurrent);
                    bal_state.active = true;
                    bal_balancing.enableBalancing = 1;
                    /* we are working with unsigned integers */
                    if (difference > bal_balancing.deltaCharge_mAs[s][c]) {
                        bal_balancing.deltaCharge_mAs[s][c] = 0;
                    } else {
                        bal_balancing.deltaCharge_mAs[s][c] -= difference;
                    }
                } else {
                    bal_balancing.balancingState[s][c] = 0;
                }
            }
        }
        bal_balancing.nrBalancedCells[s] = nrBalancedCells;
    }
 
    DATA_WRITE_DATA(&bal_balancing);
}
 
static void BAL_Deactivate(void) {
    for (uint8_t s = 0u; s < BS_NR_OF_STRINGS; s++) {
        for (uint16_t c = 0u; c < BS_NR_OF_CELL_BLOCKS_PER_STRING; c++) {
            bal_balancing.balancingState[s][c]  = 0;
            bal_balancing.deltaCharge_mAs[s][c] = 0;
        }
        bal_balancing.nrBalancedCells[s] = 0u;
    }
    bal_balancing.enableBalancing = 0;
    bal_state.active              = false;
 
    DATA_WRITE_DATA(&bal_balancing);
}
 
static void BAL_ProcessStateCheckBalancing(void) {
    if (bal_state.substate == BAL_ENTRY) {
        if (bal_state.balancingGlobalAllowed == false) {
            if (bal_state.active == true) {
                BAL_Deactivate();
            }
            bal_state.active   = false;
            bal_state.substate = BAL_ENTRY;
        } else {
            bal_state.substate = BAL_CHECK_IMBALANCES;
        }
 
        bal_state.timer = BAL_STATEMACH_SHORTTIME_100ms;
        return;
    } else if (bal_state.substate == BAL_CHECK_IMBALANCES) {
        if (bal_state.active == true) {
            BAL_Deactivate();
        }
        if (BAL_CheckImbalances() == true) {
            bal_state.state    = BAL_STATEMACH_BALANCE;
            bal_state.substate = BAL_ENTRY;
        } else {
            bal_state.substate = BAL_COMPUTE_IMBALANCES;
        }
        bal_state.timer = BAL_STATEMACH_SHORTTIME_100ms;
        return;
    } else if (bal_state.substate == BAL_COMPUTE_IMBALANCES) {
        if (BMS_GetBatterySystemState() == BMS_AT_REST) {
            BAL_ComputeImbalances();
            bal_state.state    = BAL_STATEMACH_BALANCE;
            bal_state.substate = BAL_ENTRY;
        } else {
            bal_state.substate = BAL_CHECK_IMBALANCES;
        }
        bal_state.timer = BAL_STATEMACH_SHORTTIME_100ms;
        return;
    }
}
 
static void BAL_ProcessStateBalancing(void) {
    bool activateBalancing = true;
 
    if (bal_state.substate == BAL_ENTRY) {
        if (bal_state.balancingGlobalAllowed == false) {
            if (bal_state.active == true) {
                BAL_Deactivate();
            }
            bal_state.active   = false;
            bal_state.substate = (BAL_STATEMACH_SUB_e)BAL_STATEMACH_CHECK_BALANCING;
        } else {
            bal_state.substate = BAL_ACTIVATE_BALANCING;
        }
        bal_state.timer = BAL_STATEMACH_SHORTTIME_100ms;
        return;
    } else if (bal_state.substate == BAL_ACTIVATE_BALANCING) {
        DATA_BLOCK_MIN_MAX_s bal_minmax = {.header.uniqueId = DATA_BLOCK_ID_MIN_MAX};
        DATA_READ_DATA(&bal_minmax);
        bal_state.timer = BAL_STATEMACH_BALANCINGTIME_100ms;
        /* do not balance under a certain voltage level */
        for (uint8_t s = 0u; s < BS_NR_OF_STRINGS; s++) {
            if ((bal_minmax.minimumCellVoltage_mV[s] <= BAL_LOWER_VOLTAGE_LIMIT_mV) ||
                (bal_minmax.maximumTemperature_ddegC[s] >= BAL_UPPER_TEMPERATURE_LIMIT_ddegC) ||
                (BAL_CheckImbalances() == false) || (bal_state.balancingGlobalAllowed == false)) {
                activateBalancing = false;
                if (bal_state.active == true) {
                    BAL_Deactivate();
                }
                bal_state.state    = BAL_STATEMACH_CHECK_BALANCING;
                bal_state.substate = BAL_ENTRY;
                return;
            }
        }
 
        if (activateBalancing == true) {
            BAL_ActivateBalancing();
        }
        return;
    }
}
static bool BAL_CheckImbalances(void) {
    bool retVal = false;
 
    for (uint8_t s = 0u; s < BS_NR_OF_STRINGS; s++) {
        for (uint16_t c = 0u; c < BS_NR_OF_CELL_BLOCKS_PER_STRING; c++) {
            if (bal_balancing.deltaCharge_mAs[s][c] > 0) {
                retVal = true;
            }
        }
    }
 
    return retVal;
}
 
static void BAL_ComputeImbalances(void) {
    uint16_t voltageMin      = 0;
    uint16_t minVoltageIndex = 0;
    float SOC                = 0.0f;
    uint32_t DOD             = 0;
    uint32_t maxDOD          = 0;
 
    DATA_READ_DATA(&bal_balancing, &bal_cellVoltage);
 
    for (uint8_t s = 0u; s < BS_NR_OF_STRINGS; s++) {
        voltageMin      = bal_cellVoltage.cellVoltage_mV[s][0];
        minVoltageIndex = 0;
 
        for (uint16_t c = 0u; c < BS_NR_OF_CELL_BLOCKS_PER_STRING; c++) {
            if (bal_cellVoltage.cellVoltage_mV[s][c] <= voltageMin) {
                voltageMin      = bal_cellVoltage.cellVoltage_mV[s][c];
                minVoltageIndex = c;
            }
        }
 
        SOC = SE_GetStateOfChargeFromVoltage(((float)(bal_cellVoltage.cellVoltage_mV[s][minVoltageIndex])) / 1000.0f);
        maxDOD                                            = BC_CAPACITY_mAh * (uint32_t)((1.0f - SOC) * 3600.0f);
        bal_balancing.deltaCharge_mAs[s][minVoltageIndex] = 0;
 
        /* update balancing threshold */
        bal_state.balancingThreshold = BAL_GetBalancingThreshold_mV() + BAL_HYSTERESIS_mV;
 
        for (uint16_t c = 0u; c < BS_NR_OF_CELL_BLOCKS_PER_STRING; c++) {
            if (c != minVoltageIndex) {
                if (bal_cellVoltage.cellVoltage_mV[s][c] >= (voltageMin + bal_state.balancingThreshold)) {
                    SOC = SE_GetStateOfChargeFromVoltage(((float)(bal_cellVoltage.cellVoltage_mV[s][c])) / 1000.0f);
                    DOD = BC_CAPACITY_mAh * (uint32_t)((1.0f - SOC) * 3600.0f);
                    bal_balancing.deltaCharge_mAs[s][c] = (maxDOD - DOD);
                }
            }
        }
    }
 
    DATA_WRITE_DATA(&bal_balancing);
}
 
/*========== Extern Function Implementations ================================*/
extern STD_RETURN_TYPE_e BAL_GetInitializationState(void) {
    return bal_state.initializationFinished;
}
 
extern BAL_RETURN_TYPE_e BAL_SetStateRequest(BAL_STATE_REQUEST_e stateRequest) {
    BAL_RETURN_TYPE_e retVal = BAL_OK;
 
    OS_EnterTaskCritical();
    retVal = BAL_CheckStateRequest(&bal_state, stateRequest);
 
    if (retVal == BAL_OK) {
        bal_state.stateRequest = stateRequest;
    }
    OS_ExitTaskCritical();
 
    return retVal;
}
 
extern void BAL_Trigger(void) {
    BAL_STATE_REQUEST_e stateRequest = BAL_STATE_NO_REQUEST;
 
    /* Check re-entrance of function */
    if (BAL_CheckReEntrance(&bal_state) > 0u) {
        return;
    }
 
    if (bal_state.timer > 0u) {
        if ((--bal_state.timer) > 0) {
            bal_state.triggerEntry--;
            return; /* handle state machine only if timer has elapsed */
        }
    }
 
    switch (bal_state.state) {
        case BAL_STATEMACH_UNINITIALIZED:
            BAL_SaveLastStates(&bal_state);
            stateRequest = BAL_TransferStateRequest(&bal_state);
            BAL_ProcessStateUninitalized(&bal_state, stateRequest);
            break;
        case BAL_STATEMACH_INITIALIZATION:
            BAL_SaveLastStates(&bal_state);
            BAL_Init(&bal_balancing);
            BAL_ProcessStateInitialization(&bal_state);
            break;
        case BAL_STATEMACH_INITIALIZED:
            BAL_SaveLastStates(&bal_state);
            BAL_ProcessStateInitialized(&bal_state);
            break;
        case BAL_STATEMACH_CHECK_BALANCING:
            BAL_SaveLastStates(&bal_state);
            BAL_ProcessStateCheckBalancing();
            break;
        case BAL_STATEMACH_BALANCE:
            BAL_SaveLastStates(&bal_state);
            BAL_ProcessStateBalancing();
            break;
        default:
            /* invalid state */
            FAS_ASSERT(FAS_TRAP);
            break;
    }
    bal_state.triggerEntry--;
}
 
/*========== Externalized Static Function Implementations (Unit Test) =======*/
#ifdef UNITY_UNIT_TEST
extern BAL_STATEMACH_e BAL_GetState(void) {
    return bal_state.state;
}
#endif
 
/*================== Getter for static Variables (Unit Test) ==============*/
#ifdef UNITY_UNIT_TEST
extern DATA_BLOCK_BALANCING_CONTROL_s *TEST_BAL_GetBalancingControl(void) {
    return &bal_balancing;
}
 
extern BAL_STATE_s *TEST_BAL_GetBalancingState(void) {
    return &bal_state;
}
#endif